Production of dextrose



Patented June 4, 1940 2,203,324

UNITED STATES PATENT- orricrz PRODUCTION OF DEXTBOSE Charles J. Copland, North Kansas City, Mo., assignor, by mesne. assignments, to Corn Products Refining Company, New York, N. Y., acorporation of New Jersey No Drawing. Application May 19, 1938,

,Serlal No.- 208,823

8 Claims. 127 -38) This invention relates tothe production of have been successively operated to eflect a yield crystalline dextrose from starch converted dexof crystalline dextrose from hydrol. However,

trose solutions; and the primary object of the the processes have certain disadvantages, forexinvention is to increase the dextrose yield, that I ample, the expense involved in the re-conversion b is, the amount of crystalline dextrose obtainable and the production of color in the massecuite 5 from a given quantity of solution. which is difiicult to remove.

The invention may be regarded as an improve- Where a dextrose containing solution, such as ment upon the processes described and claimed hydrol, is re-con'verted according to the method in United States patents to William B. Newkirk, disclosed, for example, in the patent to Ebert 19v No. 1,471,347, October 23, 1923-, and No. 1,521,830, et al, No. 1,704,937, referred to above, the action January 6, 1925. According to the practice under of the acid at high temperatures contemplated the patents, the converted liquor, after suitable is to change the non-crystallizable reducing refining operations and concentration to proper sugars in the solution (formed probably by condensity, is introduced into a crystallizer having a. densation of dextrose, a typical one being the slow moving agitator and supersaturation di-saccharide gentiobiose) into the crystallizable 15 brought about and maintained by cooling. After mono-saccharide, dextrose. The I reaction incrystallization, the massecuite is purged of its volves also the conversion of non-reducing sugars, mother .liquor (first greens) and washed with of higher molecular weight than gentiobiose into water in centrifugal machines. The first greens, gentiobiose or other reducing sugars.

after refining and concentration, are subjected to The present invention is based upon the dis- 20 another crystallizing operation, in a crystallizer covery that the conversion of non-crystallizable of the type mentioned, and the mother liquor sugar to dextrose can be brought about by the (hydrol) extracted from the crystals by centrifuguse of a suitable hydrolyzing or converting acid ing. The second sugar thus produced may be at, ordinary room or crystallizing temperatures, marketed as such, either with'or' without washthat is, without the high temperatures and pres- 25 ing in the centrifugal machine; or it may be sures used in the patented processes of hydrol melted with or without washing, the melt mixed re-conversion referred to above. with fresh converter liquor and the mixture used Incarrying out the new process as applied to for a subsequent first crystallizing operation. the-treatment of hydrol, the hydrol, after con- Under present practice the. second sugar will centration, is introduced into a standard type 30 have a somewhat lower purity than the first crystallizer above described, and is there mixed sugar, the purity of which may be between 99.5% with massecuite from a previous crystallizing opand 100%; and the, second crystallization will eration, preferably with massecuite or foots ordinarily be prolonged until the hydrol will be from a-second crystallizing operation; the mixincapable of further crystallization. That is, ing being'efiected by means of the agitator which 35 if the masseouite; is given the usual slow agitais set in motion in the usual manner. Because tion in a standard type of crystallizing vessel, of the concentration ofthc hydrol and change substantially no more dextrose will come out of in proportions as between solid and liquid phases,

the solution at least within a reasonable length the liquid phase being proportionately larger 40 of time. The mother liquor or hydrol is a spent in the mixture than in the massecuite from which 40 liquor so far as any practical continuation of the hydrol was purged, some crystallization will crystallization is concerned. Under these cirtake place. When this has substantially ceased cumstances, the purity; of the hydrol (reducing (or, if desired at any earlier stage of the process) sugars calculated as dextrose) will be in the hydrochloric acid, or other strong acid commonneighborhood of 67% to 69% and its dextrose ly used for the conversion of starch to dextrose, 45 content about both on dry substance basis. referred to herein as converting acid is intro- It has been proposed to re-convert the hydrol, duced into the massecuite and the slow motion in order to obtain therefrom additional crysagitation continued. Apparently the acid, which talline dextrose, by acidifying and heating it in might be added at an earlier stage, is more cf- 50 an autoclave at the steam pressures which are fective for the-purpose intended if added after customary for the conversion ofthe starch to some crystallization has taken place. The redextrose. Processes of this character are dissult'is that the dextrose content of the solution closed in the patents of Ebert, Newkirk and Mosis increased and the solution yields additional kowitz, No. 1,673,187, June 12, 1928, and No. crystallized dextrose. r v 1,704,037, March 5, 1929; and these processes A The addition of acid may be repeated from Y 100 pounds 01' 18 .informative and typical. limit the scope of the invention to the particulars time to time until no further yield of crystalline dextroseresults; or until such time as the operation ceases to be profitable, having in view the amount of additional dextrose capable of being. produced in this manner. Apparently the acid acts, without heat, which has not been heretofore suspected, upon the gentiobiose or other non-crystallizable polysaccharides to change them to crystallizable dextrose, 'whereby the so lution becomes again supersaturated in respect to dextrose. The dextrose crystallizes as the hydrate under the conditions described.

The invention, however, is not limited to the treatment of low content dextrose solutions, nor to the addition of the. acid to a massecuite after crystallization has ceased, but may be employed to increase. the dextrose content of any dextrose solution containing non-crystallizable sugars capable of being re-converted into dextrose,

through increase of the acidity of the solution treated and may be introduced into the solution at any suitable stage of the process. For example, acid may be added to the concentrated converter liquor going to the first crystallizers or to the concentrated first greens sent to the second crystallizers.

The following is a specific example of the application of the invention to the treatment of hydrol. It will be understood that this example is purely It is not the purpose to given in this example, the intention being to cover all equivalents as well as all modifications within the scope of the appended claims.

Erample.75,000 pounds of hydrol (mother liquor from a second crystallization) having a purity (reducing sugar calculated as dextrose) of 67-%69% was introduced, at a density of 415 Baum, into a standard crystallizer on 30,000 pounds of massecuite (foots) produced in a second crystallizing operation. The mixture, hydrol and foots, was cooled to 6244 F. and this temperature maintained with the agitator in slow motion,

until crystallization substantially ceased, which was after a yield 'had been reached of about 31% crystalline dextrose hydrate, based on dry substance in the massecuite. -At this point Baum hydrochloric acid was added to the massecuite and the yield increased to approximately 35%. Several more additions of acid were made from time to time until the yield reached 37%, after which no further crystallization took place. The yield figures, it will be understood, were arrived at by taking samples from the massecuite from time to time and determining the proportion between crystalline dextrose hydrate and total dry substance. When crystallization ceased, the massecuite was centrifuged and the dextrose, without washing was found to have a purity of 89.0%. The yield, on the 100% purity basis, was 20.6% of the dry substance in the hydrol treated. In this example the crystallizing period was 45 from time to time, indicated a progressivedecrease in gentiobiose and a progressive increase in dextrose.

able sugar into crystallizable dextrose.

7 days. The sanrples ofthe fillmass, solution in solid phase, taken;

converted dextrose solution conta 2. In the production of tallizable sugar, the treatment of a'substantially spent mother liquor with an acid, at a pressure not substantially above atmospheric pressure, to

able dextrose.

3. Improvement in the process 01' crystallizing dextrose from a starch tion containing non-crystallizable sugar which comprises: adding a converting acid tOvthG massecuite during the crystallizing operation to in-' 5. Treatment of substantially spent mother liquor containing non-crystallizable sugar derived from the process of making crystalline dextrose which comprises: mixing with the mother liquor massecuite from a previous crystallizing operation, adding a converting acid and maintaining the material in slow motion at a pressure not substantially above atmospheric pressure to bring about further crystallization of.dextrose.

6. Treatment oi? substantially spent mother liquor containing non-crystallizable sugar derivedirom a process 01' making crystalline dextrose which comprises: mixing the mother liquor with massecuite from a previous crystallizing operation; maintaining the material in slow motion at a pressure not substantially above atmospheric pressure; and adding, after crystallization has substantially ceased, a converting acid to change the non-crystallizable sugar into crystallizable dextrose; and continuing the slow motion agitation.

7. In the production of crystalline dextrose from starch converted dextrose solutions, containing non-crystallizable sugar in which the mother liquor from the first crystallization ,is

subjected to a second c operation, the process of treating mother liquor from the second crystallization which comprises: with said mother liquor second sugar massecmte; maintaining the mixture in slow'm'ction at a pressure not substantially above atmospheric pressure; and, after crystallization has substantially ceased, adding a converting acid and continuing the slow motion agitation.

dextrose from a starch converted dextrose solution containing non-crys change non-crystallizable sugar into crystallizconverted dextrose soluv 10 a. Process or obtaining crystalline dextrose from a starch converted dextrose solution containing non-crystallizable sugar which comprises: supersaturating the solution to bring about crystallization; removing the mother liquor from the crystal mass; subjecting the mother liquor to another crystallizing operation; extracting the hydrol from the massecuite; concentrating the hydrol and mixing therewith massecuite from a second crystallization; and subjecting the same to another crystallizing operation; and when crystallization has the massecuite a; converting the crystallizing operation.

acid and continuing substantially ceased adding to 

